Kaposi's sarcoma

Source: Wikipedia, the free encyclopedia.
Kaposi's sarcoma, multiple haemorrhagic sarcoma
Other namesKaposi sarcoma
biologic therapy[4]
Frequency42,000 (new cases, 2018)[7]
Deaths20,000 (2018)[7]

Kaposi's sarcoma (KS) is a type of

Human herpesvirus 8 (HHV8 – also called KS-associated herpesvirus (KSHV)).[8]

Classic, endemic, immunosuppression therapy-related (also known as iatrogenic), and epidemic (also known as AIDS-related) sub-types are all described.

tissue biopsy, while the extent of disease may be determined by medical imaging.[4][6][8]

Treatment is based on the sub-type, whether the condition is localized or widespread, and the person's immune function.

biologic therapy.[4][6] In those with HIV/AIDS, highly active antiretroviral therapy (HAART) prevents and often treats KS.[8][9] In certain cases the addition of chemotherapy may be required.[9] With widespread disease, death may occur.[6]

The condition is relatively common in people with HIV/AIDS and following organ transplant.

AIDS-defining illnesses in the 1980s.[11] KSHV was discovered as a causative agent in 1994.[11][13]

Signs and symptoms

KS lesions are nodules or blotches that may be red, purple, brown, or black, and are usually papular.[citation needed]

They are typically found on the skin, but spread elsewhere is common, especially the mouth,

morbidity.[14]

The lesions are painless, but become cosmetically disfiguring or interruptive to organs.[15]

Skin

An example of Kaposi's sarcoma
Patch stage Kaposi's sarcoma. Red to brownish irregularly shaped macules and plaques.[16]

Commonly affected areas include the

skin breakdown with resulting fungating lesions
. Associated swelling may be from either local
lymphatic vessels by the lesion). Kaposi's sarcoma skin lesions may be psychologically distressing.[17][18]

Mouth

An HIV-positive person presenting with a Kaposi's sarcoma lesion with an overlying candidiasis infection in their mouth

The mouth is involved in about 30% of cases, and is the initial site in 15% of AIDS-related KS. In the mouth, the hard palate is most frequently affected, followed by the gums.[19] Lesions in the mouth may be easily damaged by chewing and bleed or develop secondary infection, and even interfere with eating or speaking.[citation needed]

Gastrointestinal tract

Involvement can be common in those with transplant-related or AIDS-related KS, and it may occur in the absence of skin involvement. The gastrointestinal lesions may be silent or cause weight loss, pain, nausea/vomiting,

intestinal obstruction.[20]

Respiratory tract

Involvement of the airway can present with shortness of breath,

chest x-ray.[21] The diagnosis is usually confirmed by bronchoscopy, when the lesions are directly seen and often biopsied. Kaposi's sarcoma of the lung has a poor prognosis.[citation needed
]

Cause

microRNAs and circular RNAs that promote cancer cell proliferation and escape from the immune system.[23]

Transmission

In Europe and North America, KSHV is transmitted through saliva. Thus, kissing is a risk factor for transmission. Higher rates of transmission among gay and bisexual men have been attributed to "deep kissing" sexual partners with KSHV.[24] Another alternative theory suggests that use of saliva as a sexual lubricant might be a major mode for transmission. Prudent advice is to use commercial lubricants when needed and avoid deep kissing with partners with KSHV infection or whose status is unknown.[citation needed]

KSHV is also transmissible via organ transplantation[25] and blood transfusion.[26] Testing for the virus before these procedures is likely to effectively limit iatrogenic transmission.[citation needed]

Pathology

Micrograph of a Kaposi sarcoma showing the characteristic spindle cells, high vascularity, and intracellular hyaline globs. H&E stain.

Despite its name, in general it is not considered a true

lymphatic endothelium[30] and forms vascular channels that fill with blood cells, giving the tumor its characteristic bruise-like appearance. KSHV proteins are uniformly detected in KS cancer cells.[citation needed
]

KS lesions contain tumor cells with a characteristic abnormal elongated shape, called spindle cells. The most typical feature of Kaposi sarcoma is the presence of spindle cells forming slits containing red blood cells. Mitotic activity is only moderate and pleomorphism is usually absent.[31] The tumor is highly vascular, containing abnormally dense and irregular blood vessels, which leak red blood cells into the surrounding tissue and give the tumor its dark color. Inflammation around the tumor may produce swelling and pain. Variously sized PAS positive hyaline bodies are often seen in the cytoplasm or sometimes extracellularly.[citation needed]

The spindle cells of Kaposi sarcoma differentiate toward

podoplanin supports the lymphatic nature of the lesion.[citation needed
]

  • Micrograph of promontory sign in Kaposi's sarcoma in patch stage. Dilated irregular vascular channels surround a pre-existing vessel.[16]
    Micrograph of promontory sign in Kaposi's sarcoma in patch stage. Dilated irregular vascular channels surround a pre-existing vessel.[16]
  • Micrograph of plaque stage, with bizarre vessels dissecting the upper dermis. There is erythrocyte extravasation and hemosiderin pigmentation.[16]
    Micrograph of plaque stage, with bizarre vessels dissecting the upper dermis. There is erythrocyte extravasation and hemosiderin pigmentation.[16]
  • Micrograph of tumor stage. Well-circumscribed spindle-cell tumor. Erythrocytes lie within poorly defined slit-like vascular spaces.[16]
    Micrograph of tumor stage. Well-circumscribed spindle-cell tumor. Erythrocytes lie within poorly defined slit-like vascular spaces.[16]

Diagnosis

Although KS may be suspected from the appearance of lesions and the patient's risk factors, a definite diagnosis can be made only by biopsy and microscopic examination. Detection of the KSHV protein LANA in tumor cells confirms the diagnosis.[citation needed]

In differential diagnosis, arteriovenous malformations, pyogenic granuloma and other vascular proliferations can be microscopically confused with KS.[33]

Differential diagnosis of Kaposi's sarcoma

Source:[34]

  1. Naevus
  2. Histiocytoma
  3. Cryptococcosis
  4. Histoplasmosis
  5. Leishmaniasis
  6. Pneumocystis lesions
  7. Dermatophytosis
  8. Angioma
  9. Bacillary angiomatosis
  10. Pyogenic granuloma
  11. Melanoma

Classification

HHV-8 is responsible for all varieties of KS. Since

KSHV
and are different manifestations of the same disease but have differences in clinical aggressiveness, prognosis, and treatment.

Prevention

Blood tests to detect antibodies against KSHV have been developed and can be used to determine whether a person is at risk for transmitting the infection to their sexual partner, or whether an organ is infected before transplantation. However, these tests are not available except as research tools, and, thus, there is little screening for persons at risk for becoming infected with KSHV, such as people following a transplant.[citation needed]

Treatment

Kaposi sarcoma is not curable, but it can often be treatable for many years. In KS associated with immunodeficiency or immunosuppression, treating the cause of the immune system dysfunction can slow or stop the progression of KS. In 40% or more of patients with AIDS-associated Kaposi sarcoma, the Kaposi lesions will shrink upon first starting highly active antiretroviral therapy (HAART). Therefore, HAART is considered the cornerstone of therapy in AIDS-associated Kaposi sarcoma. However, in a certain percentage[vague] of such people, Kaposi sarcoma may recur after many years on HAART, especially if HIV is not completely suppressed.

People with a few local lesions can often be treated with local measures such as radiation therapy or

beta-blockers, such as timolol, may induce regression of localized lesions in classic as well as HIV-associated Kaposi sarcoma.[51][52] In general, surgery is not recommended, as Kaposi sarcoma can appear in wound edges. In general, more widespread disease, or disease affecting internal organs, is treated with systemic therapy with interferon alpha, liposomal anthracyclines (such as liposomal doxorubicin or daunorubicin), thalidomide, or paclitaxel.[53][54]

Alitretinoin, applied to the lesion, may be used when the lesion is not getting better with standard treatment of HIV/AIDS and chemotherapy or radiation therapy cannot be used.[55]

Epidemiology

With the decrease in the death rate among people with HIV/AIDS receiving new treatments in the 1990s, the rates and severity of epidemic KS also decreased. However, the number of people living with HIV/AIDS is increasing in the United States, and it is possible that the number of people with AIDS-associated Kaposi sarcoma will again rise as these people live longer with HIV infection.[citation needed]

Society

Because of their highly visible nature, external lesions are sometimes the presenting symptom of AIDS. Kaposi sarcoma entered the awareness of the general public with the release of the film Philadelphia, in which the main character was fired after his employers found out he was HIV-positive due to visible lesions. By the time KS lesions appear, likely, the immune system has already been severely weakened.[citation needed] It has been reported that only 6% of men who have sex with men are aware that KS is caused by a virus different from HIV.[56] Thus, there is little community effort to prevent KSHV infection. Likewise, no systematic screening of organ donations is in place.

In people with AIDS, Kaposi sarcoma is considered an opportunistic infection, a disease that can gain a foothold in the body because the immune system has been weakened. With the rise of HIV/AIDS in Africa, where KSHV is widespread, KS has become the most frequently reported cancer in some countries.

References

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  3. ^ Random House Kernerman Webster's College Dictionary. S.v. "Kaposi's sarcoma." Retrieved August 15, 2017 from http://www.thefreedictionary.com/Kaposi's+sarcoma
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